The present disclosure relates to an information handling system, and more particularly to an information handling system transitioning between various power conserving states.
As the value and use of information continues to increase, individuals and businesses seek additional ways to acquire, process and store information. One option available to users is information handling systems. An information handling system (IHS) generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, IHSs may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in IHSs allow for IHSs to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, entertainment, and/or global communications. In addition, IHSs may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
To reduce power consumption, an IHS may be placed into a variety of different activity states or operational states with differing levels of power consumption. Many sophisticated power management schemes have been developed and implemented as industry standards.
Such power management standards define a variety of operational states depending upon system activity and the amount of power being consumed. For example, the ACPI specification defines various “sleeping” states such as S1, S2, S3, S4 and S5, which are available within the G1 global sleeping state. States S1-S4 may have differing wakeup latency times (or resume times) depending upon which devices are inactive, how much computer system context was saved prior to entering the sleep state, and similar other factors. In the S3 state (also referred to as a suspend state), which is a low wake latency sleeping state, all system context is lost except system memory. Hardware platform maintains memory context and restores some processor and cache memory configuration context. Control starts from the processor's reset vector after the wake event. The S4 state (also referred to as a hibernate state) is the lowest power sleeping state and typically has the longest wake latency. Thus, while in the S4 state, the IHS system consumes a minimal amount of power. Therefore, the S4 state may be maintained for a significantly longer duration of time compared to the S3 state since the S3 state typically consumes a finite amount of power to maintain contents of the memory.
In the S4 state, typically no instructions are executed by the processor, almost all devices included in the computer system are inactive, and the computer system generally awaits occurrence of a wakeup or resume event to transition it to a higher activity state. Awakening (or resuming) from the S4 state typically requires the longest wake latency time (or resume time), especially compared to resuming from the S3 state, because the memory image containing the system context is typically loaded from an electromechanical device such as a hard disk drive (HDD) into the random access memory (RAM). Thus, the S4 resume time is presently bounded by the performance limitations of the HDD, such as the peak sustained throughput of the HDD.
Therefore, a need exists for an improved wake latency time when transitioning from a power saving sleep state to a higher activity state. More specifically, a need exists to improve the wake latency time, with tools and techniques being preferably implementable as electronic devices that have no moving parts. Accordingly, it would be desirable to provide a for improving wake latency time of an IHS, absent the disadvantages discussed above.